I understand that there is Absolute market, but that does not seem to work, can someone make a simple gui so that players can easily list things for a price of their choice 

I think the Sell tab on ServerRewards should be changed to an Auction House mod. Many people would like this mod to be mad.

I would put in. Thank you to the uMod community!

I will be starting an Auction mod in a few days. I'll probably start out basic, then release it, then flesh it out. Stand by.